The invention concerns a process for the production of a ball point pen cartridge, the ink column of which is constantly acted upon by gas pressure.
With ball point pen cartridges of this type there is the problem of creating the gas pressure in the rear part of the ink tube before the rear end of the tube is finally sealed and also to make sure that the gas pressure has the same value in the production of each cartridge and is maintained after being created. Since ball point pen cartridges are mass production articles, the production of the gas pressure must also be capable of being carried out in an economical fashion.
The familiar processes did not meet these requirements, and they were not able to guarantee uniform quality in mass production.
A familiar process consists in bringing together two chemical substances at the rear end of the ink column which react together, emitting gas, whereby the gas-emitting reaction occurred after the complete sealing of the ink tube. This process is complicated, expensive and imprecise.
Another familiar process consists in positioning a sealed capsule containing one gas in the rear, end of the ink tube and providing a stopper which has a needle, whereby the user must pierce the capsule with the needle, when putting the cartridge into use, by pushing on the stopper, in order to be able to build up the gas pressure. This process is also imprecise and relatively expensive, and besides that, the user still has to perform an operation on the cartridge.
Finally, another familiar process involves pushing a stopper into the rear end of the ink tube, whereby the air between the end of the ink column and the stopper is compressed. This process is, to be sure, relatively simple, still there are problems of sealing, and the amount of ink to be put into the ink tube is limited, because a part of the space which is needed to compress the column of air is lost as storage space for the ink.